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Andreas John's self-FAQ for VServer 2.0: developed from a dialogue with myself and answers from the mailing-list

Q. What is a "guest"?

A: In the vitualisation business we talk about "hosts" and "guests". The host is the mother operating system or mother machine, while a guest is a virtual machine or OS

Q. What kind of OS can I run as guest?

A: With VServer you can only run Linux guests. The trick is that a guest does not run an own kernel, it merely uses the hosts kernel-interface. VServer offers so called security contexts which make it possible to seperate one guest from each other, i.e. they cannot get data from each other. Imagine it as a chroot environment with much more security and features.

Q: Which distributions did you test?

A: Some. Check out the wiki for read-made guest images. But you can easily build own guests images, e.g. with Debian's debootstrap. Checkout step-by-step Guide 2.6 how to do that.

Q: Is VServer comparabale to XEN?

A: Nope. XEN and VServer are just good friends. Becuse You ask, you probably know what XEN is. VServer does in contrary to XEN not "emulate" any Hardware. You can run a VServer kernel in a XEN host and install several guests within this XEN. This is conformed to work at least with 2.6 kernel / vs20.

Q: Is VServer secure?

A: We hope so. It should be as secure as Linux is. It much much more secure

Q: Performance?

A: Nearly as the host. There is very little overhead, Herbert measured about 1-2%. This IMVHO significantly less than other solutions waste.

Q: Is SMP Supported?

A1) On the host:

A2) On the guest: Remember ... the guest uses the same kernel!

Q: Resource sharing?

A: Yes ....

Q: Resource limiting?

A: Yes, you can set max limits per guest, but you can only offer guaranteed resource availability with some ticks at the time. There is the possibility to ulimit and to rlimit. rlimit is a new feature of kernel 2.6.

Q: Why isn't there a a device /dev/bla? within a guest

A: Devices belong to the kernel and thus to the host.

Q: What is Unification (vunify)?

A:

Q: What is vhashify?

A:

Q: How do I manage a multi-guest setup with vhashify?

A: -> Herbert ;)

Q: With which VS version should I begin? I saw 2.0 is "beta" ....

A: If you are new to VServer I recommend to try 2.0. It's late beta and is likely to release soon. Kudos go to Herbert. The 2.0 release is his "baby".

U: VServer 2.0 is released. Take "aplha utils" Version 0.30-208 and Herbert additional patches for them. In Debian Sid this version is provided as package (but without vhashify as the time)

Q: is there a way to implement "user quota" per VServer?

A:

Q: And inside VServer?

A:

Q: Does it support IPv6?

A: Currently not. Some developer has to move his ... to reimplement this functionality from the V4 code (I read that on the ML ;))

Q: I can't do all I want with the network interfaces insade the guest?

A: Yes and No. You can set the capability icmp_raw in the context of the guest, or even the capability CAP_NET_RAW (which would even allow to sniff interfaces of other guests!)

Example command lines - explained:

$ foo
bar ....